docs: def export(self, nidm_version, export_dir):
          """
          Create prov entities and activities.
          """
          if nidm_version['num'] in ["1.0.0", "1.1.0"]:
              self.label = self.label.replace("Supra-Threshold", "Significant")
  
          # FIXME deal with multiple contrasts
          atts = (
              (PROV['type'], NIDM_SIGNIFICANT_CLUSTER),
              (PROV['label'], self.label),
              (NIDM_CLUSTER_LABEL_ID, self.num),
              (NIDM_CLUSTER_SIZE_IN_VOXELS, self.size)
              )
  
          if self.clust_size_resels is not None:
              atts = atts + (
                  (NIDM_CLUSTER_SIZE_IN_RESELS, self.clust_size_resels),
                  )
  
          if self.punc is not None:
              atts = atts + (
                  (NIDM_P_VALUE_UNCORRECTED,
                      Literal(self.punc, datatype=XSD_FLOAT)),
                  )
  
          if self.pFDR is not None:
              atts = atts + (
                  (NIDM_Q_VALUE_FDR, Literal(self.pFDR, datatype=XSD_FLOAT)),
                  )
  
          if self.pFWER is not None:
              atts = atts + (
                  (NIDM_P_VALUE_FWER, Literal(self.pFWER, datatype=XSD_FLOAT)),
                  )
  
          self.add_attributes(atts)